[{"categories":["Nanoantennas and Silicon Photonics","Projects"],"content":"My silicon photonics work at IBM centred on the idea of integrating submicron silicon optical waveguides with metal plasmonic antennas and metal-insulator-metal (MIM) tunnel junctions, to build optical detectors and modulators in the 1.55 μm region.\nThey use a novel plasmonic travelling-wave structure to eliminate the effects of capacitance at optical frequencies—it\u0026amp;rsquo;s the fat metal bit in the middle of the X-shaped antenna arms, shown in the figure at right.\nThe attraction of this method is that it potentially eliminates the usual drawbacks of silicon photonic switching devices: narrow optical bandwidth, extreme temperature sensitivity, and high drive power. We estimated that it could reach drive power levels of less than 40 microwatts per Gb/s (40 fJ/bit), due to its low voltage swing (100 mV) and sub-femtofarad capacitance.\nThis is the project that POEMS was written for. We demonstrated the first waveguide-integrated ACTJ detectors, which have achieved a 40-fold increase in …","description":"","tags":[],"title":"Antenna-Coupled Tunnel Junctions for Optical Interconnection","url":"/projects/antenna-coupled-tunnel-junctions-for-optical-interconnection/"},{"categories":["Simulators","Projects"],"content":"There are a variety of EM simulation schemes in wide use, with different strengths and weaknesses. For free-space antennas at radio frequency, where dielectrics are simple and metals are excellent conductors, integral equation schemes such as the method of moments (MoM) win. At optical frequencies, particularly when metal is involved, partial differential equation methods are generally better. The two most common PDE schemes are finite element method (FEM) and finite difference, time domain (FDTD). The antenna-coupled tunnel junction work required simulations with very fine resolution (1 nm) in some places, to represent plasmons and metal surface discontinuities, and a very large simulation domain, at least 5 μm square by 20 μm long. This requires multiprocessor capability and subgridding, i.e. different places in the simulation domain having different cell sizes. Subgridding is a natural strength of FE, but presents a challenge in FDTD, which naturally likes uniform cubical grids. On …","description":"","tags":[],"title":"POEMS: Programmable Optimizing Electromagnetic Simulator","url":"/projects/poems-programmable-optimizing-electromagnetic-simulator/"},{"categories":["Laser Noise Cancellers","Projects"],"content":"Laser noise is very often the primary limiting factor in making high-accuracy optical intensity measurements. There are ways of making your laser quieter, but they won\u0026amp;rsquo;t get to the shot noise level. On the other hand, what we actually measure is the photocurrent, not the laser power, and that we can improve.\nLaser Noise Cancellers are extremely powerful devices that allow us to make shot-noise limited measurements at baseband, even with very noisy lasers. With zero adjustments, they will reliably suppress the effects of laser residual intensity noise (RIN) by 55 or 60 dB from dc to several megahertz, and with a bit of (optical) tweaking, will do 70 dB or more at low frequency, which is where it\u0026amp;rsquo;s most needed (see the picture above, which shows \u0026amp;gt; 70 dB suppression of noise intermodulation). There\u0026amp;rsquo;s a New Focus app note which surveys applications of noise cancellers.\nThe laser noise canceller has two operating modes, linear and log-ratio. The linear mode produces a …","description":"","tags":["Noise Canceller","Hobbs Circuit","Signal-to-Noise Ratio","Noise","Laser Noise","Excess Noise","Residual Intensity Noise","RIN","SNR","Cancellation","Log Ratio","Logarithmic"],"title":"Laser Noise Cancellers","url":"/projects/laser-noise-cancellers/"},{"categories":["LIDAR","Ultrasensitive Measurements","Projects"],"content":"Particles in plasma etch chambers are a major source of yield loss in semiconductor manufacturing. Particles condensing from the plasma or spalling out of films on the chamber walls are levitated in the edges of the plasma sheath for long periods, and then (too often) drop on the wafer when the plasma excitation is turned off.\nProcess control and tool utilization can both be improved by knowing what\u0026amp;rsquo;s happening inside the chamber while the process is going on—but how? The plasmas are usually too bright to look at, and there\u0026amp;rsquo;s only one (poor quality) window in the typical chamber, so an optical particle detector would have to work in backscatter, with a huge background.\nISICL is capable of seeing and mapping individual particles of less than 0.2 μm diameter, as they float around in the plasma, a unique capability.\nAn interesting combination of homodyne interferometry, laser noise cancellation, and signal processing allows reliable operation at the shot noise limit in the …","description":"","tags":[],"title":"ISICL: In Situ Coherent Lidar for Submicron Particle Detection","url":"/projects/isicl-in-situ-coherent-lidar-for-submicron-particle-detection/"},{"categories":["Microscopy","Projects"],"content":"Optical phase is a wonderful thing—it can get you good topographical images of samples with no discernible amplitude contrast, for example, or allow you to disambiguate phase features from amplitude ones. My interest in phase-sensitive microscopes dates back to my graduate work—hence this paper. It gives design details and the theory of the heterodyne scanning laser microscope, including the point- and line-spread functions, plus a deconvolution method that can give resolution equivalent to an ordinary microscope working at λ0/2—ultraviolet resolution from a visible-light scope. Operating with a green Ar+2 laser (514.5 nm) and 0.9 NA, it attained a 10%-90% edge resolution of 90 nm.\nThis works because the interferometer makes it a confocal microscope, i.e. its amplitude point-spread function is the square of the illumination PSF. By the convolution theorem of Fourier transforms, that means that its bandwidth is twice as wide, i.e. ±2NA/λ. A bit of digital filtering turns the resulting …","description":"","tags":[],"title":"Heterodyne Confocal and Solid Immersion Microscopy","url":"/projects/heterodyne-confocal-and-solid-immersion-microscopy/"},{"categories":["Embedded Systems","Infared Imaging","Projects"],"content":"A low-resolution thermal camera with competitive sensitivity (0.13 K NETD) at very low cost. Easily built from scratch—it requires no special parts, except a screen-printed sheet of pyroelectric PVDF polymer (as used in automatic porch lights) and a moulded polyethylene Fresnel lens. This camera achieves a cost reduction of 2 orders of magnitude ($10 vs $1000) over the next cheapest, which is a 256-pixel PZT array from Irisys, while maintaining very good sensitivity. These are from a project called Footprints.\nThe design is simple: screen-printed carbon ink on a free-standing film of PVDF polymer, with a multiplexer made out of ordinary display LEDs with a few interesting optical and electronic hacks, as shown in these photos.\nMosaic image from 6 Footprints sensors, showing four people wandering underneath. Slightly smoothed to reduce the visual noise from all the little squares. A fun war story from the September 2003 issue of Optics \u0026amp;amp; Photonics News about the ups and downs of the …","description":"","tags":[],"title":"Footprints: A $10 Thermal Infrared Imager","url":"/projects/footprints-a-10-thermal-infrared-imager/"},{"categories":["Photoreceivers","Projects"],"content":"Specifications 3dB Bandwidth From DC–200 kHz to DC–300 MHz Rise Time 4ns (highest bandwidth configuration) Gain Control Method Gain settable by serial or analog voltage. Analog voltage control profile mimics behaviour of similar PMT modules. Detector Type Hammamatsu S13361/S13362 series or On Semi MicroFC series SiPm Coupling DC Output Impedance 50 Ω Dynamic Range All configurations support analog and photon counting Power Requirements +5V 100mA, -5V 10mA Signal Output SMA Applications Flow cytometry, Microplate readers, TOF Lidar In the last year or two we\u0026amp;rsquo;ve been doing a lot of work aimed at replacing photomultiplier tubes (PMTs) in instruments, using avalanche photodiodes (APDs) and silicon photomultipliers (SiPMs). These devices are arrays of single-photon detectors, so they\u0026amp;rsquo;re also known as multi-pixel photon counters (MPPCs). Our main application areas include biomedical instruments such as flow cytometers and microplate readers, which have to measure low light levels …","description":"ElectroOptical Innovations is offering a line of Silicon Photomultiplier (SiPM) modules designed to replace legacy photomultiplier tube modules with extended capability (low noise, wide bandwidth, and digital control), decreased cost, and improved reliability.  With a wide dynamic range, these devices can count photons and operate in analog detection mode without modifications.  The built in programmable gain amplifier and bias generator are combined to give the lowest possible noise level at the commanded gain.  The signature frontend design focuses on high linearity, low noise, and small footprint, making them suited for time-of-flight instrument LIDAR, flow cytometry, and micro-plate reader applications.  These devices are flexibly licensed and easily customizable:  voltage- or serial-controlled gain, cooled or uncooled, and with bandwidths from 200 kHz to 200 MHz.","tags":["APD","PMT","IP","SPAD","SiPm","Analog","Frontend","Hammamatsu","On Semi","MPPC","Photomultiplier","Temperature-Stabilized","Project","Signal-to-Noise Ratio"],"title":"SiPM Module","url":"/projects/sipm-module/"},{"categories":["News","Products","Ultrasensitive Instrument Design"],"content":"The LA-22 Low-Noise Laboratory Amplifier, 800 Hz–22 MHz, 1.1 nV / √Hz One problem that comes up again and again in doing measurements is that we need the apparatus to be quieter than the thing we\u0026amp;rsquo;re measuring, ideally by at least a factor of two. Besides quiet, it should be wideband, have an accurately known gain that\u0026amp;rsquo;s flat with frequency, have a clean step response, and generally do its job while keeping itself out of the way. There\u0026amp;rsquo;s a wealth of detail in our app note AN-1 on photoreceiver testing.\nTest gear is noisy, with many scopes coming in at 5-10 nV / √Hz and RF spectrum analyzers around 30 nV / √Hz. What\u0026amp;rsquo;s worse, noise contributions add in power: that 30 nV is over 1000 times noisier than its 50-Ω load resistor. The analyzer is general-purpose, and can\u0026amp;rsquo;t do everything well.\nAt EOI/HEO, we’ve run into such problems more than enough times. Thus we built ourselves an amplifier that’s good for just about anything of that sort: the LA22 Lab Amp from …","description":"","tags":[],"title":"Featured Product: LA-22 Low Noise Lab Amplifier","url":"/blog/new-product-la-22-low-noise-lab-amplifier/"},{"categories":["News","Sensitive Design"],"content":" A quick plug for a little gem of a book that all fans of early radio should know about: \u0026amp;ldquo;Super-Regenerative Receivers\u0026amp;rdquo; by J. R. Whitehead (Cambridge University Press, 1950). It\u0026amp;rsquo;s part of the Modern Radio Techniques series, where a bunch of the technical movers and shakers document the advances that were made during the war, e.g. centimeter radar. This one is about the theory and practice of superregenerative radios. I learned a lot from it and had a lot of fun.\nExcursus for folks who aren\u0026amp;rsquo;t early radio buffs (yet): A superregen is an oscillator whose gain is turned on and off at some rate by a quench signal, so that the oscillation repeatedly builds up from noise (and any RF input signal that may be present), as illustrated in Figure 1. The detected signal is the average amplitude of the oscillation. If the gain is high enough that the oscillator saturates in less than the quench ON time, an input signal whose amplitude is e times the noise level, it gives the …","description":"A quick plug for a little gem of a book that all fans of early radio should know about: \"Super-Regenerative Receivers\" by J. R. Whitehead (Cambridge University Press, 1950).  It's part of the Modern Radio Techniques series, where a bunch of the technical movers and shakers document the advances that were made during the war, e.g. centimeter radar.  This one is about the theory and practice of superregenerative radios.  I learned a lot from it and had a lot of fun.","tags":[],"title":"\"Super-Regenerative Receivers\" by J. R. Whitehead","url":"/blog/super-regenerative-receivers-by-j-r-whitehead-modern-radio-techniques-series-cambridge-1950/"},{"categories":["New Technology","News"],"content":"Temperature Control The need to control temperature is everywhere, but getting it right is more difficult than one might expect. A domestic furnace controlled by a simple thermostat keeps a house comfortable in winter, but the inside air temperature swings irregularly over a range of a few degrees. That\u0026amp;rsquo;s fine for a house\u0026amp;mdash;you can have a New Year\u0026amp;rsquo;s party, with a bunch of people dissipating a hundred watts each, doors to hot ovens and the cold outside opening and closing, no worries whatsoever. The heating system keeps it comfortable.\nSuch sloppy control doesn\u0026amp;rsquo;t work everywhere. In applications such as scientific instruments, industrial process control, tunable diode lasers, bioreactors, and high precision mechanisms, we often need much better. It\u0026amp;rsquo;s far from rare for them to need temperature control down to the millikelvin or even microkelvin range. For that, we need a better control system: tighter error limits, higher speed, and higher precision. (And …","description":"Temperature Control The need to control temperature is everywhere, but getting it right is more difficult than one might expect. A domestic furnace controlled by a simple thermostat keeps a house comfortable in winter, but the inside air temperature swings irregularly over a range of a few degrees. That's fine for a house---you can have a New Year's party, with a bunch of people dissipating a hundred watts each, doors to hot ovens and the cold outside opening and closing, no worries whatsoever.  The heating system keeps it comfortable.","tags":[],"title":"Temperature Control 1: Simple Control Theory","url":"/blog/voltage-regulators/"},{"categories":["News","Products"],"content":"In a previous article, we described an ultralow-cost time-domain reflectometer (TDR) that is used as a radar dipstick for fuel gauges in heavy equipment. Its 150-ps edges were better than good enough, and its rock-bottom BOM cost ($1.30 @ 100 pcs) made it possible for the whole gauge to retail for under $40. That performance is far from the limit for low-cost samplers, as we\u0026amp;rsquo;ll see.\nTDR01 Time Domain Reflectometer More recently, we\u0026amp;rsquo;ve been doing a higher-performance (60 ps) TDR/sampler for instrumentation: the Hobbs ElectroOptics model TDR01, which is also available for OEM and licensing. In this article, we talk about the operation of the TDR01\u0026amp;rsquo;s heart: the Tx and Rx pulsers, sampler, and sampling loop.\nThe TDR01 is a two-diode design that fits comfortably on a 25 x 60 mm PC board. It uses faster diodes and a symmetrical sampler design to achieve excellent linearity and stray pulse rejection, making it suitable for instrumentation use. The BOM isn\u0026amp;rsquo;t quite …","description":"In a previous article, we described an ultralow-cost time-domain reflectometer (TDR) that  is used as a radar dipstick for fuel gauges in heavy equipment.  Its 150-ps edges were better than good enough, and its rock-bottom BOM cost ($1.30 @ 100 pcs) made it possible for the whole gauge to retail for under $40.  That performance is far from the limit for low-cost samplers, as we'll see.","tags":[],"title":"A High-Performance Time Domain Reflectometer","url":"/blog/a-high-performance-time-domain-reflectometer/"},{"categories":["News","Products"],"content":"\nWe’ve got a new photoreceiver available over at our sister site, Hobbs ElectroOptics. The QL03 Photoreceiver comes out of several proof-of-concept systems where we needed a high-sensitivity, low-noise optical receiver for low-light applications.\nIt features a massive 150 mm² photodiode with slight magnification from an immersion lens, making it especially effective for diffuse light measurements, spectroscopy, and fluorescence detection—plus, setup is a breeze since you’re aiming at a barn door.\nWith a 1 MΩ transimpedance gain and DC–750 kHz bandwidth, it offers a rare combination of high sensitivity, fast response, and low noise, delivering shot-noise-limited performance above 100 nA across its full bandwidth.\nA carefully designed bootstrap topology enables this unusual balance of speed, noise performance, and collection area. Built to handle real lab conditions, the QL03 is engineered to make precision optical measurements as easy as possible.\nMore details at hobbs-eo.com.\n","description":"We've got a new photoreceiver available over at our sister site, Hobbs ElectroOptics. The QL03 Photoreceiver comes out of several proof-of-concept...","tags":[],"title":"Product Announcement: QL03 Photoreceiver","url":"/blog/product-announcement-ql03-photoreceiver/"},{"categories":["News","SED","Ultrasensitive Instrument Design"],"content":"One of the most enjoyable parts of electronics design is getting excellent performance with rock-bottom parts cost. The right circuit can produce exceptionally good speed, noise, and accuracy specs from very low-cost parts. A case in point was a project from December 2016: a time-domain reflectometer (TDR) for a liquid level sensing application in industry.\nTDRs work by sending short pulses down a transmission line where they bounce off anything that disturbs their propagation. By measuring the time delay, you can tell how far down the line the disturbance is. It\u0026amp;rsquo;s a bit like a one-dimensional radar, except that with TDR you can learn a lot more from the reflection than just its location. TDRs can find damaged optical fibres, waterlogged sections of coax cable, and many other things of that sort. This application used an air-dielectric coaxial probe built from two metal tubes sticking downwards into a tank, so that the first part of the probe had air as dielectric and the second …","description":"","tags":[],"title":"A 150-Picosecond Time Domain Reflectometer for Under $2","url":"/blog/150-ps-tdr-for-under-2/"},{"categories":[],"content":"We\u0026amp;rsquo;ve published our first full-scale application note: AN-1: Photoreceiver Testing System . Based on our LP870 Nanosecond Light Source and LA22 Lab Amplifier, the system gives an easy and economical way to test photoreceivers as fast as 5 ns. In the time domain, it measures rise and fall times with excellent accuracy. In the frequency domain, it measures the noise floor (down to below 1 nV/√Hz), both dark and light, and gives a neat hack for measuring the transimpedance vs. frequency to very high accuracy.\n","description":"","tags":[],"title":"Application Note: Photoreceiver Testing","url":"/blog/application-note-photoreceiver-testing/"},{"categories":["Electronics","Optics"],"content":"Placeholder for a PMT article on photon counting, low-current analogue mode vs. MPPCs, and the high linearity version\n","description":"","tags":[],"title":"Photomultipliers: There's a Lot to Love","url":"/articles/photomultipliers-theres-a-lot-to-love/"},{"categories":["Electronics","Optics"],"content":"We often get asked questions like, \u0026amp;ldquo;How do I know what photodetector is best for (application X)?\u0026amp;rdquo; For some values of X, it\u0026amp;rsquo;s pretty simple: if you\u0026amp;rsquo;ve got milliwatts of visible light, use a silicon PIN photodiode and an ordinary transimpedance amp (TIA) made from an op amp or (for faster things) a packaged 50-ohm RF amplifier. It\u0026amp;rsquo;s usually easy to verify that you\u0026amp;rsquo;re in the shot noise limit\u0026amp;mdash;if your photocurrent drops more than 50 mV across its load impedance, you\u0026amp;rsquo;re there. (*)\nThat\u0026amp;rsquo;s a super useful rule, but you do have to watch out for another noise source: the eNC effect due to the shunt capacitance.\n**Figure 1:** Simple noise model of a transimpedance amplifier. Thermal, shot, and amplifier current noise contributions add as currents, while the amplifier voltage noise gets multiplied by the noninverting gain of the stage. Figure 1 shows a simple noise model of a transimpedance amp. There are three current noise sources: shot …","description":"We often get asked questions like, \"How do I know what photodetector is best for (application X)?\" For some values of X, it's pretty simple: if you've got milliwatts of visible light, use a silicon PIN photodiode and an ordinary transimpedance amp (TIA) made from an op amp or (for faster things) a packaged 50-ohm RF amplifier. It's usually easy to verify that you're in the shot noise limit---if your photocurrent drops more than 50 mV across its load impedance, you're there. (*)","tags":[],"title":"What Photodetector Should I Use for Application 'X'?","url":"/articles/what-photodetector-should-i-use-for-application-x/"},{"categories":[],"content":"","description":"Contact ElectroOptical Innovations by phone, email, or mail.","tags":[],"title":"Contact","url":"/pages/contact/"},{"categories":["News","Products","Sensitive Design","Ultrasensitive Instrument Design"],"content":"Internal Developments\nIn the last year or two we\u0026amp;rsquo;ve been doing a lot of work aimed at replacing photomultiplier tubes (PMTs) in instruments, using avalanche photodiodes (APDs) and silicon photomultipliers (SiPMs). These devices are arrays of single-photon detectors, so they\u0026amp;rsquo;re also known as multi-pixel photon counters (MPPCs). Our main application areas include biomedical instruments such as flow cytometers and microplate readers, which have to measure low light levels very precisely but don\u0026amp;rsquo;t need the ultralow dark current of PMTs. (Follow-on articles will talk about our SiPM work in airborne lidar and SEM cathodoluminescence, as well as on improving the performance of actual PMTs.)\nPMTs have been around since the 1930s, and remain the undisputed champs for the very lowest light levels. We love PMTs, but we have to admit that they\u0026amp;rsquo;re delicate and not that easy to use—they tend to be bulky, they need high voltage, and they need regular replacement. Most of all, …","description":"Internal DevelopmentsIn the last year or two we've been doing a lot of work aimed at replacing photomultiplier tubes (PMTs) in instruments, using avalanche photodiodes (APDs) and silicon photomultipliers (SiPMs).  These devices are arrays of single-photon detectors, so they're also known as multi-pixel photon counters (MPPCs).  Our main application areas include biomedical instruments such as flow cytometers and microplate readers, which have to measure low light levels very precisely but don't need the ultralow dark current of PMTs. (Follow-on articles will talk about our SiPM work in airborne lidar and SEM cathodoluminescence, as well as on improving the performance of actual PMTs.)PMTs have been around since the 1930s, and remain the undisputed champs for the very lowest light levels.  We love PMTs, but we have to admit that they're delicate and not that easy to use—they tend to be bulky, they need high voltage, and they need regular replacement.  Most of all, PMTs are very expensive.","tags":["SiPm","MPPC","PMT","Photomultiplier","Frontend","Module","Noise","Hammamatsu","APD","SPAD","SEM"],"title":"Silicon Photomultiplier Module Design","url":"/blog/silicon-photomultiplier-module-design/"},{"categories":["News","Sensitive Design","Ultrasensitive Instrument Design"],"content":"In Part 1, we discussed ways to get better measurements by improving the signal to noise ratio (SNR), and saw that although it was often a win to measure more slowly and use lowpass filters, going too far actually makes things worse, because of the way noise concentrates at low frequency. Here we introduce a more sophisticated approach that generally works better: the lock-in amplifier.\nWe were considering a typical baseband signal, one that goes from near DC to some much higher frequency. Audio is a typical example, with a bandwidth usually quoted as 20 Hz to 20 kHz. To escape the low frequency noise, we need to move our signal up in frequency, out of baseband. In lock-in detection we make the signal periodic in time at some carrier frequency fc chosen to be several times higher than the required bandwidth. This is generally pretty easy to do, as we\u0026amp;rsquo;ll see, and doing so ensures that none of the signal we care about remains near DC. Our noise rejection filter now needs to be a …","description":"In Part 1, we discussed ways to get better measurements by improving the signal to noise ratio (SNR), and saw that although it was often a win to measure more slowly and use lowpass filters, going too far actually makes things worse, because of the way noise concentrates at low frequency.  Here we introduce a more sophisticated approach that generally works better: the lock-in amplifier.","tags":[],"title":"Signal to Noise Ratio and You, Part 2","url":"/blog/signal-to-noise-ratio-and-you-part-2/"},{"categories":["News","SED","Ultrasensitive Instrument Design"],"content":"In building an ultrasensitive instrument, we\u0026amp;rsquo;re always fighting to improve our signal-to-noise ratio (SNR). The SNR is the ratio of signal power to noise power in the measurement bandwidth, and is limited by noise in the instrument itself and the noise of any background signals, such as the shot noise of the background light or the slight hiss of a microphone.\nIf the signal is weak, it will have proportionally more noise, so that the apparatus has to be designed to get rid of as much noise as possible. There are a number of ways to do this. The best is to get more signal or reduce the noise, for instance by increasing the laser power and using a laser noise canceller, but eventually we hit a practical limit. At that point, we\u0026amp;rsquo;re left with several options, all of which boil down to filtering in one form or another.\nFilters can be hardware or software, but their job is to pass the desired signal frequencies and reject noise at other frequencies. Of course some of the noise …","description":"","tags":[],"title":"Signal to Noise Ratio and You, Part 1","url":"/blog/digital-lock-in-principles/"},{"categories":["Sensitive Design","Ultrasensitive Instrument Design"],"content":"Thermoelectric (Peltier) Coolers A thermoelectric cooler is a solid-state device made from two alumina ceramic plates with an array of metallized pillars in between. The pillars are also ceramic\u0026amp;ndash;they\u0026amp;rsquo;re made of alternating p-type and n-type bismuth telluride (Bi2Te) semiconductors, alloyed with antimony telluride (p-type) or bismuth selenide (n-type), and connected in series electrically. The Peltier effect makes them electric-powered solid state heat pumps. (Thermocouples work the other way round, via the Seebeck effect, but the physics is the same.)\nA recent review paper gives an interesting look at the state of the art and the many open questions in thermoelectric research. (You wouldn\u0026amp;rsquo;t think that solid-state beer fridges had such interesting physics inside, but they do.)\n(Source: Wikimedia Commons. Note that real TECs have an even number of pillars so that both wires attach to the hot side, avoiding a massive heat leak through the heavy copper wire.) …","description":"Thermoelectric (Peltier) Coolers A thermoelectric cooler is a solid-state device made from two alumina ceramic plates with an array of metallized pillars in between.  The pillars are also ceramic--they're made of alternating p-type and n-type bismuth telluride (Bi2Te) semiconductors, alloyed with antimony telluride (p-type) or bismuth selenide (n-type), and connected in series electrically.  The Peltier effect makes them electric-powered solid state heat pumps.   (Thermocouples work the other way round, via the Seebeck effect, but the physics is the same.)","tags":[],"title":"Technology: Low Noise Thermoelectric Cooler (TEC) Controllers","url":"/blog/technology-low-noise-thermoelectric-cooler-tec-controllers/"},{"categories":["SED"],"content":"James Elbert (Jim) Thompson was a well-known chip designer who used to be a regular on sci.electronics.design. He last posted in July 2018. As he was very sick at the time, we presume that he has died, but no obituary has so far turned up. He was born on February 29th, 1940, and used to say that he was looking forward to his 21st birthday in 2024.\nJim had a consulting company, Analog Innovations LLC, and a website, http://www.analog-innovations.com. You can find it on web.archive.org, but those copies are incomplete. A complete archive (minus a bit of javascript) is here at\nhttps://electrooptical.net/static/oldsite/www.analog-innovations.com/logo.html\n(main frame) and\nhttps://electrooptical.net/static/oldsite/www.analog-innovations.com/analog-innovations.html\n(navigation panel).\nJim designed many highly influential ICs, some of whose datasheets are posted on his site.\nMay God hold him in memory eternal.\n","description":"","tags":["Jim Thompson","Analog-Innovationscom","Analog","Ic Design","Scielectronicsdesign","Website Archive","MC4044","MC1530"],"title":"Mirror of www.analog-innovations.com (Jim Thompson's site)","url":"/blog/mirror-of-wwwanalog-innovationscom-jim-thompsons-site/"},{"categories":["News","SED"],"content":"InGaAs heterojunction FETs are magic parts—fast, strong, and extremely quiet. They\u0026amp;rsquo;re also called pseudomorphic high electron-mobility transistors (pHEMTs), because they use a 2D quantum well to to force the conduction electrons to move in a plane without much scattering. My fave Avago ATF38143 pHEMT was discontinued, but luckily Mini-Circuits stepped into the breach with their very nice SAV-551+ and its siblings, which are similar enough that the ATF SPICE model can be hacked up to work with them. (RF companies like Mini-Circuits never seem to supply SPICE models for some reason.) In one post on the \u0026amp;lsquo;purpose of precision\u0026amp;rsquo; thread on sci.electronics.design, I noted that the Avago ATF38143 model I had posted awhile back predicted way, way too much low frequency noise. The real pHEMTs tend to have a pretty accurately 1/f PSD with corner frequencies between 10 and 50 MHz and flatband noise of around 0.3 nV/√Hz, about 10 dB quieter than the best JFETs, as well as being 20 …","description":"","tags":[],"title":"Low Frequency Noise In InGaAs Heterojunction FETs","url":"/blog/low-frequency-noise-in-ingaas-heterojunction-fets/"},{"categories":["News","Ultrasensitive Instrument Design"],"content":"At EOI, we\u0026amp;rsquo;ve been building advanced instruments for a long time. One reason for our success is our large inventory of working designs, and another is the way we go about doing it. This post walks through a typical sort of development plan for a challenging customer requirement, in the form of a hypothetical email proposal outline for a fibre-coupled noninvasive glucose sensor similar to the one we did in 2013.\n(You can also read about a recent project that went a lot like this, except with a single prototype stage.)\nDear George:\nI hope you and yours are doing well.\nThe blood solute project is an interesting one that will make a difference to a lot of people, and promises to be good business as well. We\u0026amp;rsquo;ve enjoyed working with your team thus far\u0026amp;ndash;they\u0026amp;rsquo;re sharp and good to work with, so I expect it\u0026amp;rsquo;ll be a lot of fun. The project goals as outlined focus on getting a working preproduction version through an FDA animal study as soon as possible, with a close …","description":"","tags":[],"title":"How We Work","url":"/blog/how-we-work/"},{"categories":["Projects"],"content":"In How We Work, we gave an overview of how we build instruments, from the initial feasibility calculation (or photon budget) to delivery of the first production units.\nEach project is different, of course, but there are common themes. Here\u0026amp;rsquo;s a description of these steps from our most recent one at this writing (late January 2020), which is a low-cost cathodoluminescence detection system for use in scanning electron microscopes (SEMs).\nPhoton Budget Cathodoluminescence Principles A SEM works by scanning a tightly-focused beam of high-energy electrons (1 keV - 30 keV) across a sample, and looking at the stuff that comes out. For ordinary imaging you usually look at backscattered and secondary electrons, but there are other modes. For instance, you can get a lot of information about the sample\u0026amp;rsquo;s chemical composition by looking at the x-rays it emits. Most samples will also emit some amount of light, a process called cathodoluminescence .\nInGaN crystal imaged in SEM + CL mode …","description":"Progress of a recent project from customer request to shipping product","tags":["IP","Calculate","Intellectual Property","License","Outline","Photon Budget","Plan","Productize","Project","Proof of Concept","Prototype","Cathodoluminescence","SEM","Microscopy","Microscope","Product"],"title":"Silicon Photomultiplier (SiPM, MPPC) System for Cathodoluminescence","url":"/articles/silicon-photomultiplier-cathodoluminescence-detector/"},{"categories":["Projects"],"content":"At EOI, we\u0026amp;rsquo;ve been building advanced instruments very successfully for a long time. One reason for our success is our large inventory of working designs, and another is the way we go about doing it. This post walks through a typical sort of development plan for a challenging customer requirement. Here are the usual steps, in the form of a hypothetical email proposal outline for a fibre-coupled noninvasive glucose sensor similar to this one.\n(You can also read about a recent project that went a lot like this, except with a single prototype stage.)\nDear George:\nI hope you and yours are doing well.\nThe blood solute project is an interesting one that will make a difference to a lot of people, as well as being financially promising. Your team looks like a very good group of people to work with, so I expect it\u0026amp;rsquo;ll be a lot of fun. The project goals as outlined focus on getting a working preproduction version through an FDA animal study as soon as possible. A focus on design for …","description":"Short outline of a typical project: a brief proposal for a hypothetical noninvasive blood glucose sensor","tags":["Project","Plan","Outline","Photon Budget","Proof of Concept","Prototype","Productize","Calculate","License","Intellectual Property","IP"],"title":"How We Work: An Example","url":"/articles/how-we-work/"},{"categories":["News","Ultrasensitive Instrument Design"],"content":"In How We Work, we gave an overview of how we build instruments, from the initial feasibility calculation (or photon budget) to delivery of the first production units.\nEach project is different, of course, but there are common themes. Here\u0026amp;rsquo;s a description of these steps from our most recent one at this writing (late January 2020), which is a low-cost cathodoluminescence detection system for use in scanning electron microscopes (SEMs).\nPhoton Budget Cathodoluminescence Principles A SEM works by scanning a tightly-focused beam of high-energy electrons (1 keV - 30 keV) across a sample, and looking at the stuff that comes out. For ordinary imaging you usually look at backscattered and secondary electrons, but there are other modes. For instance, you can get a lot of information about the sample\u0026amp;rsquo;s chemical composition by looking at the x-rays it emits. Most samples will also emit some amount of light, a process called cathodoluminescence .\nInGaN crystal imaged in SEM + CL mode …","description":" In How We Work, we gave an overview of how we build instruments, from the initial feasibility calculation (or photon budget) to delivery of the first production units.","tags":["APD","Photomultiplier","SEM","SPAD","SiPm","Analog","MPPC","Microscope","Microscopy","Photon Budget","Noise","Module","Prototype","Ultraquiet","Thermoelectric Cooler","Product"],"title":"Silicon Photomultiplier (SiPM, MPPC) System for Cathodoluminescence","url":"/blog/silicon-photomultiplier-sipm-mppc-system-for-cathodoluminescence/"},{"categories":["News","Ultrasensitive Instrument Design"],"content":"Here at EOI we have three main kinds of project. One is our internal technology development projects. Some of these fail, mostly because they tend to be insanely hard, but the ones that pay off give us important new capabilities.\nThe second is research projects with customers, trying to push technological limits in fields such as biochip DNA sequencing, nanoantennas for infrared detection, ultrahigh resolution optical microscopy, hypersonic lidar, and (closer to home) infrared remote controls for consumer electronics. Those ones are a bit sporty, but succeed more often than not.\nThe third and most usual is customer work aimed at product development. These projects almost always succeed. On the rare occasions when they don\u0026amp;rsquo;t, it\u0026amp;rsquo;s generally because of client imperatives such as cancelling an already-funded project, whether for internal reasons or because the exernal funding went away. (Of course we aren\u0026amp;rsquo;t perfect either\u0026amp;mdash;I\u0026amp;rsquo;ve already posted a project from 20 …","description":"","tags":[],"title":"Noninvasive Transcutaneous Blood Glucose: A War Story","url":"/blog/transcutaneous-blood-glucose-a-war-story/"},{"categories":["Books","Electronics","Optics"],"content":"Classic Books On Electro-Optics and Circuits In Softcopy There\u0026amp;rsquo;s also the 100 Good Books list from Building ElectroOptical Systems.\nBooks on Electro-Optics Photomultipliers: Their Cause And Cure Part 1 Photomultipliers: Their Cause And Cure Part2 And Front Matter RCA Photomultiplier Handbook RCA Electro-Optics Handbook (1974) \u0026amp;ldquo;The Intensity Interferometer\u0026amp;rdquo; by R. Hanbury Brown MIL-HDBK-141: Optical Design Table of Contents through Chapter 6 (pdf) Chapters 7 through 12 (pdf) Chapters 13 through 16 (pdf) Chapters 17 through 20 (pdf) Chapters 21 through 23 (pdf) Chapter 24 through Index (pdf) And, courtesy of the good folks at Any2DJVU:\nTable of Contents through Chapter 6 (djvu format, OCRed) Chapters 7 through 12 (djvu format, OCRed) Chapters 13 through 16 (djvu format, OCRed) Chapters 17 through 20 (djvu format, OCRed) Chapters 21 through 23 (djvu format, OCRed) Chapter 24 through Index (djvu format, OCRed) Books on Early Radio Relevant to Electro-Optics Many of these …","description":"","tags":[],"title":"Good Books","url":"/articles/good-books/"},{"categories":["Electronics","Equipment"],"content":"Here\u0026amp;rsquo;s a partial list of EOI\u0026amp;rsquo;s lab equipment. The list is heavily weighted towards electronic stuff, but we also have a very complete set of high precision optical and optomechanical parts: mounts, translation and rotation stages, lenses, prisms, polarization optics, gratings, filters, modulators, detectors, lasers, and fibres, for a start. This lets us try out new ideas quickly and build test setups to verify them.\nIf you\u0026amp;rsquo;re also a fan of classical equipment, you can download manuals at Keysight (formerly Agilent, formerly HP) and Tektronix, liberatedmanuals.com, BAMA, Kurt\u0026amp;rsquo;s Manuals, ElektroTanya.com, and K04BB. KE5FX\u0026amp;rsquo;s GPIB Tools are pretty serviceable and also free. (NB: Keysight for some reason doesn\u0026amp;rsquo;t allow deep links to their support pages—you have to go through the main page and select \u0026amp;ldquo;support\u0026amp;rdquo;.)\nSend me an email and let\u0026amp;rsquo;s talk about your application.\n~Dr. Philip C. D. Hobbs, Principal\nElectronic Gear Oscilloscopes …","description":" Here's a partial list of EOI's lab equipment. The list is heavily weighted towards electronic stuff, but we also have a very complete set of high precision optical and optomechanical parts: mounts, translation and rotation stages, lenses, prisms, polarization optics, gratings, filters, modulators, detectors, lasers, and fibres, for a start. This lets us try out new ideas quickly and build test setups to verify them.","tags":[],"title":"Lab Equipment List","url":"/pages/equipment/"},{"categories":["News","SED"],"content":"There are widespread shortages of electronics parts at the moment, especially passives. Quoted factory lead times are 40 weeks or thereabouts, and since the industry is capacity-limited, it isn\u0026amp;rsquo;t clear that the situation is going to get better any time soon, so everybody\u0026amp;rsquo;s starting to panic. Given all this churn I\u0026amp;rsquo;ve been spending an unconscionable amount of time lately finding suitable replacements for out-of-stock parts.\nHigh value ceramic caps are the worst\u0026amp;ndash;their capacitance drops by at least 60% and at worst 95% at rated voltage, so finding an adequate substitute involves a lot more than the package, value and voltage rating. Most of their data sheets are useless, which is frustrating. However, all is not lost: most makers have websites where you can look at the C(V) curves.\nHere\u0026amp;rsquo;s an alphabetical list. Many of these links can also be used for resistors, inductors, and other component types as well.\nAVX SpiCat spicat.avx.com (This one is super …","description":"","tags":[],"title":"High-Value Ceramic Capacitors: They Stink, and You Can't Get Them Anyway","url":"/blog/high-value-ceramic-capacitors-they-stink-and-you-cant-get-them-anyway/"},{"categories":["News","Sensitive Design"],"content":"From the cutting room floor at Building Electro-Optical Systems, Third Edition:\nPhotographic Film\nOkay, okay. Photographic film isn\u0026amp;rsquo;t a detector of the sort we\u0026amp;rsquo;ve been discussing. Film is so out of fashion, so inconvenient. It needs messy chemicals. Getting it to be highly sensitive requires all sorts of 1960s alchemy such as pre-flashing and hypersensitizing in a forming gas or hot hydrogen atmosphere. Why do we care about it at all, in these days of 4k x 4k CMOS imagers?\nThere are two reasons. The first is that a telescope has a lot more than 4k x 4k resolvable spots. The Palomar Schmidt has a 6.6\\degrees\\ square field. At 1 arcsecond resolution, its plates were digitized at 23040 pixels square for the Digital Palomar Observatory Sky Survey (DPOSS). That\u0026amp;rsquo;s 530 Mpel, which is a lot of imager chips, but just one photographic plate. The plate can be digitized later on a scanning microdensitometer that also has many more than 4k x 4k resolvable spots. Even an ordinary …","description":"From the cutting room floor at Building Electro-Optical Systems, Third Edition:","tags":[],"title":"BEOS outtakes: Photographic Film","url":"/blog/photographic-film/"},{"categories":["SED"],"content":"Measuring temperature is surprisingly subtle. There are lots of sensors out there; Digikey sells thermistor sensors interchangeable to +- 0.1 C from several vendors for about $3 in onesies. IC sensors tout good accuracy and linearity, and come in both analogue and digital versions for way under a buck. So what\u0026amp;rsquo;s the issue?\nThe issue is: temperature sensors measure the temperature of the sensor, whereas what we want is the temperature of something else: air, fluid, or some solid object we\u0026amp;rsquo;re trying to control. So the problem is to get the sensor temperature to track the temperature we actually care about. IC sensors are especially bad, because they have stout leads made of copper (400 W/m/K thermal conductivity) and small packages made of plastic (0.1 W/m/K). Thus they basically measure the temperature of their leads, and are horrible at measuring air temperature, for instance.\nNational Semiconductor used to put out a very useful Temperature Measurements Handbook. Since TI …","description":"","tags":[],"title":"Temperature Measurement is Hard","url":"/blog/temperature-measurement-is-hard/"},{"categories":[],"content":" Pizzafil Sensor2small Sidestacksmall Sensorasmall ","description":"Footprints Project","tags":[],"title":"Footprints Project","url":"/pages/footprints/"},{"categories":["SED"],"content":"Decap picture of a Terabeam CD3109 APD/TIA module, taken with a lens glued to a cell\nphone camera\n","description":"Decap picture of a Terabeam CD3109 APD/TIA module, taken with a lens glued to a cellphone camera","tags":[],"title":"Decap Photo of Terabeam APD Photoreceiver","url":"/blog/decap-photo-of-terabeam-apd-photoreceiver/"},{"categories":["SED","Sensitive Design"],"content":"This odd circuit is an on-chip temperature balancer that uses thermal runaway to force N transistor arrays to all run at the same temperature. BJT dissipation goes up at low temperature, with very high gain. Here\u0026amp;rsquo;s its step response.\n","description":"This odd circuit  is an on-chip temperature balancer that uses thermal runaway to force N transistor arrays to all run at the same temperature.  BJT dissipation goes up at low temperature, with very high gain.  Here's its step response.","tags":[],"title":"Thermal Runaway Found Useful","url":"/blog/thermal-runaway-found-useful/"},{"categories":["SED"],"content":"Sine wave generation is a perennial problem.\nDirect-digital synthesis (DDS) uses a bunch of counters, lookup tables, and DACs,\nbut that\u0026amp;rsquo;s a relatively heavyweight solution that doesn\u0026amp;rsquo;t fit all problems.\nBJT differential pairs naturally have a hyperbolic tangent (tanh) characteristic, which can be used to round off a triangle wave into a very passable sine. I\u0026amp;rsquo;m not old enough to have invented this technique, but here are a couple of illustrations of how it works: TANH Sine Wave Shaper (PDF) and TANH Sine Wave Shaper (Mathcad).\n","description":"","tags":[],"title":"Sine Wave Generation with TANH Wave Shaper","url":"/blog/sine-wave-generation-with-tanh-wave-shaper/"},{"categories":["SED"],"content":"Solid tantalum capacitors have a lot of advantages: very low inductance in surface mount packages, ESR low but not so low that your LDO regulators start oscillating; and good capacitance per unit volume. Unfortunately they\u0026amp;rsquo;re also prone to burn up when mistreated, which makes many engineers wary of them. This war story, entitled What a Cap-astrophe! talks about how to treat them properly, and how a bit of TLC after soldering can restore their full performance.\n","description":"","tags":[],"title":"Care and Feeding of Tantalum Capacitors","url":"/blog/care-and-feeding-of-tantalum-capacitors/"},{"categories":["SED"],"content":"For RF folks, one of the perennial quests is for better frequency mixers: lower distortion,\nlower power, better spurious performance. FETs can help. Nowadays CMOS muxes are the devices of choice for HF mixers, but to get the best performance, you still have to know how they work. Ed Oxner was a long-time Siliconix apps guy, and his paper on High dynamic range FET RF mixers is still right up there with the best. (From a Siliconix databook, 1985.) The FET mux approach is often credited to Dan Tayloe, but since they work just the same, the \u0026amp;ldquo;Tayloe mixer\u0026amp;rdquo; should really be called the \u0026amp;ldquo;Oxner mixer\u0026amp;rdquo;.\n","description":"","tags":[],"title":"High Dynamic Range FET Bridge Mixers","url":"/blog/high-dynamic-range-fet-bridge-mixers/"},{"categories":["SED"],"content":"Erroll Dietz is a remarkable fellow. He started out at National Semiconductor as Bob Pease\u0026amp;rsquo;s\ntechnician, and rose to become Chief Technology Officer.\nFeedback amplifiers generally have an output impedance that rises linearly with frequency\u0026amp;mdash;in other words, it\u0026amp;rsquo;s\ninductive. As Dietz\u0026amp;rsquo;s short paper from Electronic Design shows, this effective inductance can\nresonate with the output bypass capacitor to cause really nasty noise peaks in the 1-100 kHz region. If you have an inexplicable noise peak in that range, a small resistor (a few tenths of an ohm to an ohm or two) in series with the regulator output can be just the ticket. You can also put it in series with the cap, but if you do that, make sure it\u0026amp;rsquo;s a pulse-withstanding type, or it\u0026amp;rsquo;s liable to blow up by an output short-circuit, or even the inrush transient, e.g. if somebody runs your gizmo off batteries.\nModern high-value multilayer ceramic caps (MLCCs) and aluminum-polymer electrolytics can have …","description":"","tags":[],"title":"Noise Peaks From  Linear Voltage Regulators","url":"/blog/noise-peaks-from-linear-voltage-regulators/"},{"categories":["SED"],"content":"Sometimes it\u0026amp;rsquo;s useful to add supporting documents, schematics, scope photos, simulations or other things to Usenet posts. By popular request I\u0026amp;rsquo;ve added links to some of these, in no particular order.\nA trick for turning the usual proportional/integral (PI) loop filter of a phaselocked loop (PLL) into a sweep generator for lock acquisition.\nA big slide deck with ideas on Getting Photodetection Right (from a talk given at BBN in Cambridge MA)\nA presentation from Texas Instruments showing detailed measurements of the switching noise of their OPA2188 chopper amp.\nA paper from LIGO on components with low flicker noise\n","description":"","tags":[],"title":"Random resources from my Usenet posts on sci.electronics.design","url":"/blog/random-resources-from-my-sed-posts/"},{"categories":["SED"],"content":"One of the nice things about sci.electronics.design is that it\u0026amp;rsquo;s widely redistributed by archive sites, some of which you can also use for posting, which is good since Google Groups no longer links to Usenet.\nSome examples:\nelectronics-related\nNarkive\nElectron Depot\nIt\u0026amp;rsquo;s really better to use a proper newsreader such as Thunderbird or Forte Agent. You can get a free Usenet account from Eternal September, and cheap ones from Supernews or astraweb.\nSED has been around for a long time. Archives going back to 1993 are available from Archive.org, and have a lot, a lot of good stuff. (Plus the usual allotment of Usenet flame wars and so on.)\n","description":"","tags":[],"title":"How To Read SED: Archive Sites and Newsfeeds","url":"/blog/how-to-read-sed-archive-sites-and-newsfeeds/"},{"categories":["Expert Witness Cases","News"],"content":"This was a patent and trade secret case concerning lidar (laser radar) technology for self-driving cars and trucks. It was the biggest case I\u0026amp;rsquo;ve worked on, with potential damages over $2 billion, and also one of the most fun. I was the defendant\u0026amp;rsquo;s expert on the patent side, and we beat Google\u0026amp;ndash;they dropped all their patent assertions. (This was made a lot easier by the fact that Uber wasn\u0026amp;rsquo;t infringing, of course.)\nWaymo is a former business unit of Google, and now a sister company. They were alleging that Anthony Levandowski, former head of their self-driving car effort (Google\u0026amp;rsquo;s Project Chauffeur) stole over 14,000 files containing their trade secrets when he founded his own companies Ottomotto and Otto Trucking, and brought them with him when he sold Ottomotto to Uber. That\u0026amp;rsquo;s the part that has had the tech world chewing popcorn and watching for the last year or so.\nThe trade secret side of the case settled dramatically at the end of the first week …","description":"","tags":[],"title":"Expert Case: Waymo LLC v. Uber Technologies, Inc., et al.","url":"/blog/waymo-llc-v-uber-technologies-inc-et-al/"},{"categories":["News"],"content":"Thanks to the efforts of our newest member, Simon Hobbs, we have a new web site with a new look and lots of new content, with more to come. We hope you enjoy it!\n","description":"","tags":[],"title":"New Web Site","url":"/blog/new-web-site/"},{"categories":[],"content":"In this one I was engaged as a testifying expert for the plaintiff in an action for patent infringement in optical time-domain reflectometers (OTDRs) used for testing fibre-optic networks. As so often happens, the defendant petitioned the Patent Office for an inter partes review of the patents-in-suit, which I also assisted with. The most unusual feature of this one was the really ferocious protective order covering the defendants\u0026amp;rsquo; source code\u0026amp;ndash;it had to be printed on blue paper, one hard copy only, no soft copy, and kept locked in a steel cabinet at all times when not actively in use.\nI did an extensive review of the relevant parts of the source code to identify infringing features, and wrote a declaration in claim construction. The case settled soon afterwards.\n","description":"","tags":[],"title":"EXFO Inc. et al. v Viavi Solutions, Inc.","url":"/blog/exfo-inc-iet-al-vi-viavi-solutions-inc/"},{"categories":["Expert Witness Cases","News"],"content":"In the spring of 2017, I was approached by lawyers from two technology companies working in civil avionics (instruments for airplanes). I can\u0026amp;rsquo;t say who they were due to NDA restrictions, but the job was an unusual and interesting one. The two companies had been joint development partners, but the relationship had soured and trust had now broken down completely. Both were concerned that the other was misusing intellectual property disclosed during the joint venture, and they asked me to do do an audit to see whether this was in fact true. The situation was made more complicated because one company was several hundred times as large as the other, and of course there was no court-ordered discovery and no one was under oath.\nAfter interviewing engineers for both sides and visiting SmallCo\u0026amp;rsquo;s facility, I was able to report that SmallCo\u0026amp;rsquo;s development pattern was essentially unaltered following their interaction with BigCo, and that in fact there was no evidence that BigCo …","description":"","tags":[],"title":"Neutral Referee in IP dispute between former joint development partners","url":"/blog/neutral-referee-in-ip-dispute-between-former-joint-development-partners/"},{"categories":[],"content":"Come on into the EOI lab and we\u0026amp;rsquo;ll show you around!\nWe\u0026#39;ll start with my office door and pan around to the right. Since I do a lot of stuff on B-size vellum, the antique drafting table is appropriate. The print is Botticelli\u0026#39;s Madonna del Libro. Here I\u0026#39;m in the middle of going over the schematics for an ultrastable cavity-locked laser (Allen variance \u0026lt; 1E-10 @ 100,000 seconds) A clean office is a sign of an empty mind, but I can\u0026#39;t show what it actually looks like now. Since this picture was taken, I\u0026#39;ve acquired two SuperMicro 250 Gflops servers for this room. They have dual 12-core, 64-bit Opterons, hardware RAID, and a bunch of ECC memory, mostly to run POEMS simulations for customers. One runs CentOS 6.5ES Linux and the other Qubes OS v.3.2. Their very high bandwidth to main memory is their main virtue for FDTD. I keep old databooks, because they have a lot of curves and tables that aren\u0026#39;t in the more recent datasheets. I also like old technical books a lot—the ones written by …","description":"Lab Tour Come on into the EOI lab and we'll show you around!","tags":[],"title":"Lab Tour","url":"/pages/lab-tour/"},{"categories":["Expert Witness Cases"],"content":"Testifying defense expert representing Samsung in an action for patent infringement concerning optical storage, holographic optical elements, tracking servos, and signal integrity.\n","description":"","tags":[],"title":"Voxpath RS, LLC v. Desay A\u0026V Science and Technology Co. Ltd, et al.","url":"/blog/voxpath-rs-llc-v-desay-av-science-and-technology-co-ltd-et-al/"},{"categories":["Expert Witness Cases"],"content":"This was another fun one with a lot of reverse engineering. This time round I was working with the plaintiff, Industrial Technology Research Institute, which is a research lab owned by the Taiwanese government. It was an action for patent infringement in the focusing and tracking servos of optical disc drives, as well as in the arrangement of the laser sources. The patent claims at issue concerned the way the magnetic \u0026amp;ldquo;voice coil\u0026amp;rdquo; actuators simultaneously adjusted focus, tracking, and tilt, so I needed to take several of the accused products apart and run the head servos by themselves in my lab. I also had to cut apart some of the coils to show how they were wired, and decap the lasers to show that there were two chips side-by-side in the CD/DVD source and one in the BluRay source.\nThe case settled before the expert reports on infringement were due, apparently quite favourably to our side, though one usually doesn\u0026amp;rsquo;t hear the details.\n","description":"","tags":[],"title":"Industrial Technology Research Institute v. LG Corporation, et al.","url":"/blog/industrial-technology-research-institute-v-lg-corporation-et-al/"},{"categories":["Expert Witness Cases"],"content":"Testifying expert representing ThinkOptics in an action for patent infringement concerning video games, specifically the human interface of the Nintendo Wii.\nFebruary 15, 2015: Settled after an inter partes re-examination.\n","description":"","tags":[],"title":"ThinkOptics, Inc. v. Nintendo of America, et al.","url":"/blog/thinkoptics-inc-v-nintendo-of-america-et-al/"},{"categories":["Expert Witness Cases"],"content":" Particle counter showing gold mirror This was quite an unusual situation. Dr. Aleksandr L. Yufa had several patents relating to optical particle counting, and tried to get various companies to license them. I don\u0026amp;rsquo;t know if any actually signed up, but obviously some didn\u0026amp;rsquo;t, because he sued several manufacturers and users of these technologies for infringement. The unusual part was that Dr. Yufa was acting pro se, that is, he was acting as his own lawyer.\nI was retained as testifying expert by defense counsel in two of these cases: Yufa v. Lockheed-Martin and Yufa v. Hach Ultra-Analytics*.* An inter partes review had significantly narrowed the scope of Dr. Yufa\u0026amp;rsquo;s patents. After reviewing the schematics, mechanical drawings, and source code for the accused instruments, and doing a bunch of reverse engineering and data-taking, I was able to demonstrate that there was no infringement of the remaining claims. The Court agreed, and granted the motion of summary judgment in …","description":"This was quite an unusual situation.  Dr. Aleksandr L. Yufa had several patents relating to optical particle counting, and tried to get various companies...","tags":[],"title":"Two strange cases: Yufa v. Lockheed Martin and Yufa v. Hach Ultra-Analytics","url":"/blog/yufa-v-lockheed-martin/"},{"categories":["Expert Witness Cases"],"content":"An interesting though brief patent interference case concerning flat-panel solar concentrators. The plaintiff (Morgan) had filed a continuation patent application, which is a means of getting additional claims out of a previously-filed specification. The new patent gets the same priority date as the old one, so you don\u0026amp;rsquo;t have to worry about later art (such as that of the competitor whom you want to pay you royalties), but you don\u0026amp;rsquo;t get the usual 20-year patent lifetime. Morgan then came after Banyan.\nThese concentrators are made by gluing together complicated sheets of plastic which have reflecting and guiding structures inside, so that the light comes in the flat side and goes out the edge of the sheet. That means you don\u0026amp;rsquo;t need as many expensive solar cells. Banyan, whom I was working with, had managed to avoid the asserted patent claims\u0026amp;ndash;all except one, which I had to tell them was a direct hit. Of course that ended my usefulness to them, but that\u0026amp;rsquo;s how …","description":"","tags":[],"title":"Morgan Solar v. Banyan Energy","url":"/blog/morgan-solar-v-banyan-energy/"},{"categories":["Expert Witness Cases"],"content":"It isn\u0026amp;rsquo;t easy defending an IP lawsuit in the Eastern District of Texas.\nThis was a long-running case alleging patent infringement and trade secret misappropriation. Chipmaking company Intersil Inc. wanted to get into the market for ambient light sensors (ALS). An ALS is a tiny chip that goes into phones and other battery-powered devices, which lets the processor know how brightly lit the device\u0026amp;rsquo;s surroundings are. That lets it adjust display brightness automatically to compensate, which saves battery power in dim surroundings and keeps the display from being too bright or too dim.\nThe leading ALS chip maker at the time was Texas Advanced Optoelectronics Systems (TAOS), which was a spinoff from Texas Instruments. (Local boys made good: strike one in the EDT.) Intersil approached TAOS about an acquisition, and was favourably received. The two sides did their due diligence, and Intersil made an offer to purchase TAOS. The offer was too low for TAOS\u0026amp;rsquo;s taste, owing to …","description":"","tags":[],"title":"Texas Advanced Optoelectronic Solutions, Inc. v. Intersil, Inc.","url":"/blog/texas-advanced-optoelectronic-solutions-inc-v-intersil-inc/"},{"categories":["Design Support Consulting"],"content":"Drift and 1/f Noise at 70-90 °C\nSometimes you have to find out things that aren\u0026amp;rsquo;t in the datasheet, and even the manufacturer may not know.\n","description":"Drift and 1/f Noise at 70-90 °CSometimes you have to find out things that aren't in the datasheet, and even the manufacturer may not know.","tags":[],"title":"InGaAs Photodiode Characterization Drift and 1/f  Noise at 70-90 °C","url":"/blog/ingaas-photodiode-characterization-drift-and-1f-noise-at-70-90-c/"},{"categories":["Design Support Consulting"],"content":"Thermoacoustic fridges are magic: you heat one end, and the other end gets cold. (Of course you have to sink all that heat from the middle.) They can easily be made long and skinny, and so are a natural for use down drillholes. They\u0026amp;rsquo;re also made entirely of metal, and have no moving parts, so they will survive bouncing around in the back of a truck.\nThis was a design study for a general purpose fridge for 2-inch cased holes (38 mm maximum OD) that would solve many of the temperature problems of downhole operation for a wide variety of sensors.\n","description":"","tags":[],"title":"Thermoacoustic Refrigeration","url":"/blog/thermoacoustic-refrigeration/"},{"categories":["Design Support Consulting"],"content":"This was a photon budget for an OCT system—interesting primarily for the effect of path delay in turning FM noise in the superluminescent diode (SLD) into AM noise in the measurement.\n","description":"","tags":[],"title":"Transdermal glucose detectors based on optical coherence tomography","url":"/blog/transdermal-glucose-detectors-based-on-optical-coherence-tomography/"},{"categories":["Design Support Consulting"],"content":"I chaired a series of formal design reviews for a start-up company making immersive displays with resolution better than the human eye.\n","description":"","tags":[],"title":"Mixed-reality head-mounted projection displays","url":"/blog/mixed-reality-head-mounted-projection-displays/"},{"categories":["Design Support Consulting"],"content":"Another Della project for the Navy: I did a photon budget that showed that this could be done optically within the power and weight constraints, and would work in bright sun as well as at night. (Optical communications are much harder to intercept or to jam than radio.)\n","description":"","tags":[],"title":"All-Optical Downlink for Antisubmarine Warfare (ASW) sonobuoys","url":"/blog/all-optical-downlink-for-antisubmarine-warfare-asw-sonobuoys/"},{"categories":["Design Support Consulting"],"content":"A shootout between the two major classes of transimpedance amplifier (TIA) designs for one difficult corner of the design space.\n","description":"","tags":[],"title":"Integrating vs. TIA front ends for compressive-scan cameras","url":"/blog/integrating-vs-tia-front-ends-for-compressive-scan-cameras/"},{"categories":["Design Support Consulting"],"content":"When you\u0026amp;rsquo;re hitting a droplet with enough pulsed CO2 light to generate X-rays efficiently, you have to know exactly when it\u0026amp;rsquo;s going to cross the focus.\n","description":"","tags":[],"title":"13.5 nm EUV Lithography: Tin Droplet Detection System","url":"/blog/135-nm-euv-lithography-tin-droplet-detection-system/"},{"categories":["Design Support Consulting"],"content":"Producing an integrated model of circuit conditions and ion motion, allowing optimization of circuit and excitation parameters, plus sanity checking\n","description":"","tags":[],"title":"RF Design for Ion Trap Mass Spectrometer RGA","url":"/blog/rf-design-for-ion-trap-mass-spectrometer-rga/"},{"categories":["Ultrasensitive Instrument Design"],"content":"In cooperation with Flatfrog Laboratories AB, Lund, Sweden. This one was interesting mostly due to the requirement for high and stable performance at an absolute rock-bottom cost.\n","description":"","tags":[],"title":"Touch Panel Displays: Low-Cost Optical Front End","url":"/blog/touch-panel-displays-low-cost-optical-front-end/"},{"categories":["Ultrasensitive Instrument Design"],"content":"This was a seedling design study for a DARPA program that never got funded. It leveraged POEMS and my antenna-coupled tunnel junction devices, adding a couple of novel wrinkles: metal-insulator-metal varactors and parametric readout using a 10 GHz pump frequency. Hopefully there will be a chance to revisit this, because it was potentially a pretty sweet solution.\n","description":"","tags":[],"title":"Plasmonic Nano-Antennas for Thermal Infrared Pixels","url":"/blog/plasmonic-nano-antennas-for-thermal-infrared-pixels/"},{"categories":["Ultrasensitive Instrument Design"],"content":"For a large Far Eastern consumer electronics manufacturer to use in virtual reality games. A greatly improved transimpedance amplifier got them a factor of 10 in range (30 m vs. 3 m) for about the same amount of power.\n","description":"","tags":[],"title":"Long-range IR transceiver","url":"/blog/long-range-ir-transceiver/"},{"categories":["Ultrasensitive Instrument Design"],"content":"Photon Budget and Optical Data Receiver\nThis one was a somewhat similar application for the Navy.\n","description":"Photon Budget and Optical Data ReceiverThis one was a somewhat similar application for the Navy.","tags":[],"title":"Aircraft Carrier Flight Deck Optical Communications Link","url":"/blog/aircraft-carrier-flight-deck-optical-communications-link/"},{"categories":["Ultrasensitive Instrument Design"],"content":"This was a collaboration with Chris Wieland of Della Enterprises on an Army Research contract.\n","description":"","tags":[],"title":"Ad Hoc Optical Battlefield Network: Optical Data Receiver","url":"/blog/ad-hoc-optical-battlefield-network-optical-data-receiver/"},{"categories":["Ultrasensitive Instrument Design"],"content":"This was in collaboration with a start-up in New Mexico called Symphony Acoustics. Downhole measurements are notoriously difficult, and this one was no exception: building a laser that could achieve an Allan variance of 10-10 at 10,000 seconds, and do it 5000 feet down a 2-inch cased drillhole. Due to the casing thickness, the maximum outer diameter of the instrument package was 38 mm, including its own casing and two concentric zones of thermal control.\nThe stabilization strategy was one I patented in about 1992: Send the beam through a fixed etalon; detect both the reflected and transmitted beams; form a linear combination C = T-αR for some convenient value 0 \u0026amp;lt; α \u0026amp;lt; 1; and servo the laser tuning to null out C, which can be done very accurately, without needing a high finesse cavity. The key observation is that by choosing α correctly, you can completely eliminate the coupling between AM and FM laser noise, so that besides excellent laser stability, you can also get outstandingly …","description":"","tags":[],"title":"Downhole Interferometry: Cavity-Stabilized 1550-nm Laser","url":"/blog/downhole-interferometry-cavity-stabilized-1550-nm-laser/"},{"categories":["Ultrasensitive Instrument Design"],"content":"This was in cooperation with Mesa Photonics of Santa Fe NM. It\u0026amp;rsquo;s part of a DOE program, an advanced deployable solar occultation spectrometer for detecting volatile plumes from clandestine uranium enrichment.\nTheir scheme uses a really cool technique: solar heterodyne detection. It\u0026amp;rsquo;s a good illustration of the importance of a photon budget.\n","description":"","tags":[],"title":"Nuclear Nonproliferation: 100-MHz Noise Cancelling Front End","url":"/blog/nuclear-nonproliferation-100-mhz-noise-cancelling-front-end/"},{"categories":["Ultrasensitive Instrument Design"],"content":"A follow-on to the single channel version. This one had to work at very much lower power, which required a new amplifier topology based on local feedback around a very low noise JFET. This was a very fruitful development, which has been used in a number of follow-on designs.\n","description":"","tags":[],"title":"32-Channel IR Detector for Compressive Scanning Camera","url":"/blog/32-channel-ir-detector-for-compressive-scanning-camera/"},{"categories":["Ultrasensitive Instrument Design"],"content":"In cooperation with InView Technology. Compressive scanning is a scheme for doing image sensing with a single-element detector, without suffering the N2 speed penalty of raster scanning. It\u0026amp;rsquo;s a sort of combination of scanning and image compression—you use a digital micromirror device (DMD) to multiply the image by a series of 1-bit digital basis functions, measure the resulting photocurrent, and then invert the transform to produce a compressed image. That\u0026amp;rsquo;s not too useful in the visible, where image sensors are cheap commodity items, but in the UV and especially the shortwave IR (SWIR), image arrays are extremely expensive, so there\u0026amp;rsquo;s a need for compressive scan cameras.\nThis front end had to reach the shot noise limit with high-capacitance SWIR photodiodes at very low photocurrents, which is a difficult combination.\n","description":"","tags":[],"title":"Compressive-Scan Camera: 1-Channel IR Detector Analog Front End","url":"/blog/compressive-scan-camera-1-channel-ir-detector-analog-front-end/"},{"categories":["Ultrasensitive Instrument Design"],"content":"Discussion on the topic here.\nThis one came from a a major industrial research laboratory: near shot noise limited detection of 1 nA currents in 100 MHz bandwidth.\nThis was one that I wasn\u0026amp;rsquo;t at all sure would work: it\u0026amp;rsquo;s pretty sporty trying to detect a few dozen electrons at 100 MHz in a built-up circuit. (A 100-MHz lowpass has a time-domain response about 5 ns wide, and 1 nA in 5 ns is 31 electrons.) Obviously to get the highest available signal voltage, the input-node capacitance has to be absolutely the minimum possible: less than 1 pF.\nDoing this required another novel transimpedance design, and the use of microwave transistors: 20 GHz GaAs pHEMTs and 40 GHz SiGe:C bipolars. Because performance verification of such a device is very difficult, I also designed an on-board calibrator that used the same sorts of devices to produce a 50-kHz triangular wave that was really really triangular: the corner showed less than 1 ns of curvature. When differentiated by a very small …","description":"","tags":[],"title":"Current Amplifier for Nanopore Biochips for DNA Sequencing","url":"/blog/current-amplifier-for-nanopore-biochips-for-dna-sequencing/"},{"categories":["Ultrasensitive Instrument Design"],"content":" 60 dB of laser RIN cancellation out to \u0026amp;gt; 10 MHz, about 100 times faster than current commercial devices\n","description":"","tags":[],"title":"Instrumentation: Wideband Laser Noise Canceller","url":"/blog/instrumentation-wideband-laser-noise-canceller/"},{"categories":["Ultrasensitive Instrument Design"],"content":"Using POEMS to design waveguides, coupling structures, and optical/chemical interaction regions; consulting on microfabrication issues\n","description":"Using POEMS to design waveguides, coupling structures, and optical/chemical interaction regions; consulting on microfabrication issues","tags":[],"title":"Spectroscopic-Detection Biochips Based on Photonic Waveguides","url":"/blog/spectroscopic-detection-biochips-based-on-photonic-waveguides/"},{"categories":["Ultrasensitive Instrument Design"],"content":"This is for for a scanning surface potential measurement tool, used in contamination detection in semiconductors: 40 attocoulomb sensitivity in a 4 MHz bandwidth\n","description":"","tags":[],"title":"Bootstrap Charge Sensitive Front End","url":"/blog/bootstrap-charge-sensitive-front-end/"},{"categories":["Ultrasensitive Instrument Design"],"content":"This was a prototype of a transcutaneous (through-the-skin) sensor for blood glucose and blood alcohol.\nOptical and optomechanical design, detection and control electronics and software, prototype construction: first spectra were taken 5/16/2013, and technology transfer to a contract engineering firm was essentially completed 6/14/2013.\nMost notable was the schedule requirement: from a standing start, in less than 6 weeks\u0026amp;rsquo; work, I did a complete photon budget, designed and built all of the optics and electronics, wrote all the software, integrated and shipped the system. It worked great.\nBecause of the schedule, the prototype was built mostly out of stuff I had in my drawer. That meant that all the coatings were mistuned, which cost a lot of light, but it nevertheless works very well. There are a few amusing features.\nFor instance, the grating is mounted on a servomotor intended for radio-controlled airplanes. While rather unorthodox, this is actually a pretty sweet solution for …","description":"","tags":[],"title":"SWIR Grating Spectrometer Proof of Concept","url":"/blog/swir-grating-spectrometer-proof-of-concept/"},{"categories":["Ultrasensitive Instrument Design"],"content":"A bit of a departure from our usual fare: a low cost, high speed sensor for detecting blood spots in eggs using spectral differencing. I\u0026amp;rsquo;m going to be doing the firmware as well as the optics and electronics, and this will be the first actual client work for our newly qualified PCB designer, Magdalen.\nCompeting devices use xenon flashtubes and very expensive photodiodes, but still need a lot of calibration and tweaking. That makes it a good candidate for our signature technique: A really careful photon budget followed by a design that actually reaches the theoretical optimum performance.\nEgg grading is a good example of a measurement dominated by nuisance data: normal variations between samples that have to be distinguished from the thing you\u0026amp;rsquo;re looking for. Big eggs, small eggs, white eggs, brown eggs, thick and thin shells, double yolks, mottling, you name it.\nHigh speed egg-grading machines can inspect and pack as many as 250,000 eggs per hour; running two shifts a day, …","description":"","tags":[],"title":"Blood Detector for Egg Grading","url":"/blog/blood-detector-for-egg-grading/"},{"categories":["Ultrasensitive Instrument Design"],"content":"This is a research project with a small division of a very large manufacturer. It\u0026amp;rsquo;s a complete optical/electronic design to measure optical absorbance in a rapidly moving assay plate.\n","description":"","tags":[],"title":"Plate Reader for Water Quality Assay","url":"/blog/plate-reader-for-water-quality-assay/"},{"categories":["Ultrasensitive Instrument Design"],"content":"This is a smaller job for a sensor manufacturer, interesting mostly for the size, weight, and power (SWaP) requirements. It has to be shot noise limited above 500 pA with a 1600 pF photodiode. (This is possible only because the bandwidth is relatively small.)\n","description":"","tags":[],"title":"Shot-Noise Limited Sub-Nanoamp Photoreceiver for Spectroscopy","url":"/blog/shot-noise-limited-sub-nanoamp-photoreceiver-for-spectroscopy/"},{"categories":["Ultrasensitive Instrument Design"],"content":" This is a very exciting development, in cooperation with a semiconductor equipment manufacturer. Back in 1989, my colleagues and I started working on a contact-lens microscope for looking into the interior of silicon chips through the back surface. In 1992 I took a picture (shown above) at a numerical aperture of 2.5, with resolution equivalent to NA 3.5 due to a confocal design.\nThe combination of this with my thesis work on doubling conventional microscope resolution via heterodyne interferometry and digital filtering was going to allow us to take images at an equivalent numerical aperture of 6.4. I never got to build the full scale system.\nNow, over 20 years later, I finally get to do it for real. I\u0026amp;rsquo;m designing and prototyping a microscope to work at NA 6.4, which will have resolution on the order of 15 nm (10%-90% rise). That\u0026amp;rsquo;s pretty cool stuff for a visible-light microscope, and if it works, it should give me bragging rights for a long, long time.\n","description":"This is a very exciting development, in cooperation with a semiconductor equipment manufacturer. Back in 1989, my colleagues and I started working on a contact-lens microscope for looking into the interior of silicon chips through the back surface. In 1992 I took a picture (shown above) at a numerical aperture of 2.5, with resolution equivalent to NA 3.5 due to a confocal design.  The combination of this with my thesis work on doubling conventional microscope resolution via heterodyne interferometry and digital filtering was going to allow us to take images at an equivalent numerical aperture of 6.4. I never got to build the full scale system. Now, over 20 years later, I finally get to do it for real. I'm designing and prototyping a microscope to work at NA 6.4, which will have resolution on the order of 15 nm (10%-90% rise). That's pretty cool stuff for a visible-light microscope, and if it works, it should give me bragging rights for a long, long time.","tags":[],"title":"Doubling the Resolution of Solid Immersion Microscopes: Update","url":"/blog/doubling-the-resolution-of-solid-immersion-microscopes-1/"},{"categories":["SED"],"content":" This is pretty small, because it has to be\u0026amp;ndash;those are microwave transistors, and will oscillate at the slightest provocation. The axial resistors and TO-92 parts are all for biasing\u0026amp;mdash;the actual amplifier is the part between the output coupling cap (the small orange thing in the middle) and the photodiode, which is the white square with the black middle at the right.\nThe 0.1-inch pitch holes round the outside and 25-mil pad pitch set the scale.\nThis amp works fine below 6 mA of bias current, but above there it wants to oscillate at 6 GHz. Interestingly this is just what SPICE predicts if the capacitance across the cascode device\u0026amp;rsquo;s base isolation bead is about 0,2 pF, which is a plausible number.\n","description":"This is pretty small, because it has to be--those are microwave transistors, and will oscillate at the slightest provocation. The axial resistors and TO-92 parts are all for biasing---the actual amplifier is the part between the output coupling cap (the small orange thing in the middle) and the photodiode, which is the white square with the black middle at the right.","tags":[],"title":"Cascode Enhancement pHEMT Photodiode Preamp","url":"/blog/cascode-enhancement-phemt-photodiode-preamp/"},{"categories":["SED"],"content":"As discussed in medium-gory detail in this paper, laser noise cancellers can let you do shot-noise limited measurements at baseband with lasers that are as much as 70 dB noisier than that.\nThey\u0026amp;rsquo;re limited by two main effects: beta nonlinearity (1/hFE-1/hfe) and log nonconformance (d ln(IC)/dVBE - kT/e).\nThis tester measures both of these quantities directly. It\u0026amp;rsquo;s a one-off, of course, so it\u0026amp;rsquo;s done with discrete logic and instrumentation amp parts. It has certain points of interest, for instance the use of a unity gain instrumentation amplifier as a precision +1/+2 gain amplifier. One loose end: U1 is a LT1043 switched-capacitor building block—a glorified MUX that has very low charge injection and very good common-mode rejection.\nSchematic and data for the transistor tester ","description":"As discussed in medium-gory detail in this paper, laser noise cancellers can let you do shot-noise limited measurements at baseband with lasers that are as much as 70 dB noisier than that.","tags":[],"title":"Transistor Tester for laser noise canceller","url":"/blog/transistor-tester-for-laser-noise-canceller/"},{"categories":["Expert Witness Cases","News"],"content":"Sometimes the expert has to tell the client that their case probably won\u0026amp;rsquo;t hold up. This case was an excellent example: University of Cincinnati v. Crayola, Inc.\nAs happens so often, the defendant had petitioned for a reexamination of the asserted patent, and I was asked by the plaintiff to help out. The patent-in-suit was a division of an older case, so the specification had a lot of good inventive stuff in it, but the actual claims of this patent concerned ultraviolet-activated fluorescent displays (the black-light ones you see in bars and restaurants that you write on with a fluorescent marker). An interesting idea, for sure, but one that has been in wide use since the 1960s at least.\nThe defendant/petitioner pulled up a lot of prior art, including a Web catalogue from the Wayback Machine (archive.org) that showed the same kind of boards and fluorescent markers being offered for sale a decade before the priority date of the patent. As far as I could see, they met every one of …","description":"","tags":[],"title":"Inter Partes Review for Fluorescent Bar Signs","url":"/blog/inter-partes-review/"},{"categories":["Expert Witness Cases","News"],"content":"January 2013 - June 2015.\nHere I was a testifying expert working with the plaintiff in a case involving the fancy voice-coil electromagnetic actuators that control tracking and focus in optical disc drives (CD, DVD, BluRay). I did a lot of reverse engineering, including driving the actuators and taking video showing their operation, unwinding the coils to show their winding pattern and connections, that sort of thing. The case was stayed for quite awhile and then settled, so full reports and testimony weren\u0026amp;rsquo;t required.\n","description":"","tags":[],"title":"Industrial Technology Research Institute v. LG Electronics et al.","url":"/blog/industrial-technology-research-institute-v-lg-electronics-et-al/"},{"categories":["Expert Witness Cases"],"content":"November 2009 to March 2015\nThis was a very large ($100M) action for alleged patent infringement and trade secret misappropriation concerning ambient light sensor (ALS) chips. (These allow your phone to adjust the screen brightness to optimize readability and battery life.) I was testifying expert for the defendant on the trade secret side of the case, working with the late Dr. A. Bruce Buckman on the patent side. After an unsuccessful negotiation for Intersil to acquire TAOS, Intersil developed its own line of ALS chips. TAOS sued, alleging that these were based on TAOS intellectual property.\nI was able to demonstrate to my own satisfaction that Intersil had not used TAOS\u0026amp;rsquo;s technology, but unfortunately, and apparently due to some document retention irregularities, the East Texas jury found them liable. (The Intersil manager who initiated the engagement had apparently used a non-standard contract that Intersil\u0026amp;rsquo;s legal department didn\u0026amp;rsquo;t know about and that had much …","description":"","tags":[],"title":"Texas Advanced Optoelectronic Solutions (TAOS) v. Intersil Inc.","url":"/blog/texas-advanced-optoelectronic-solutions-taos-v-intersil-inc/"},{"categories":["News"],"content":"I\u0026amp;rsquo;m testifying in my first trial, as an expert witness on the trade secret side of a complicated lawsuit alleging patent infringement, trade secret misappropriation, among other things. As a technical expert, I have to sit through the whole three-week trial to make sure I don\u0026amp;rsquo;t miss any relevant testimony, even though I\u0026amp;rsquo;ll probably be on the stand for no more than three or four hours. It\u0026amp;rsquo;s actually pretty interesting.\n","description":"","tags":[],"title":"At Trial in TAOS v Intersil","url":"/blog/at-trial-in-taos-v-intersil/"},{"categories":["News"],"content":"Coherent laser radar (often miscalled lidar) is an ultrasensitive method for measurement of distance and radial velocity. It uses low power CW lasers and has excellent resistance to ambient light and interference from other laser radars. I\u0026amp;rsquo;m doing a design for a unit suitable for vehicles and small ships (e.g. tugboats).\n","description":"","tags":[],"title":"Coherent Laser Radar for Vehicles and Navigation","url":"/blog/coherent-laser-radar-for-vehicles-and-navigation/"},{"categories":["News"],"content":"This is a very exciting development, in cooperation with a semiconductor equipment manufacturer, I\u0026amp;rsquo;m building a visible-light scanning microscope with six times higher lateral resolution than is possible with a normal microscope. It\u0026amp;rsquo;s based on my Ph.D. thesis work and some things I did at IBM long ago.\n","description":"","tags":[],"title":"Doubling the Resolution of Solid Immersion Microscopes","url":"/blog/doubling-the-resolution-of-solid-immersion-microscopes/"},{"categories":["Expert Witness Cases","News"],"content":"January-September 2014\nSometimes you just get blindsided. Back in the mid-1960s, shortly after the laser was invented, a couple of smart guys named Norman Wild and Paul Leavy were working for a defense contractor in New Hampshire called Sanders Associates (now part of BAE Systems). They came up with a clever idea for spotting snipers on a battlefield, based on a laser and a special property of the eye. Most of us have seen the way a cat\u0026amp;rsquo;s eyes seem to glow in the dark: their retinas are retroreflectors much like a bicycle reflector or a safety vest, that send light back preferentially the way it came. Human retinas do that too, though not quite as obviously. (Before smart digital cameras, photos taken with direct flash tended to show people\u0026amp;rsquo;s eyes glowing bright red for this reason.)\nAnyway, Wild and Leavy realized that a sniper\u0026amp;rsquo;s eye looking through a rifle scope was a very efficient retroreflector that could be detected from a long distance, at least if he was …","description":"","tags":[],"title":"Optical Devices LLC v. Lenovo et al.","url":"/blog/optical-devices-llc-v-lenovo-et-al/"},{"categories":["News"],"content":" Based in large part on my expert reports and reverse engineering of accused products, our Motion for Summary Judgment was granted. In the order, Judge Beverly O\u0026amp;rsquo;Connell stated that the defendant \u0026amp;ldquo;\u0026amp;hellip;has shown that Plaintiff has failed to produce evidence to support his claims for patent infringement.\u0026amp;rdquo;\nThis is especially satisfying to me, since although I had been retained only in September, the case had been dragging on for over six years, and a previous motion for summary judgment had been denied. (The only drawback is that I had been looking forward to testifying in January.)\n","description":"Based in large part on my expert reports and reverse engineering of accused products, our Motion for Summary Judgment was granted. In the order, Judge Beverly O'Connell stated that the defendant \"...has shown that Plaintiff has failed to produce evidence to support his claims for patent infringement.\"","tags":[],"title":"Summary Judgment Granted In Yufa v. Lockheed Martin","url":"/blog/summary-judgment-granted-in-yufa-v-lockheed-martin-1/"},{"categories":["News"],"content":" Three interesting new engineering projects have come in: a microplate reader subsystem for water quality assays; a sensor front end with very stringent size, weight, and power (SWaP) constraints; and a scanning microscopy development system.\n(Picture credit: https://en.wikipedia.org/wiki/File:Microplate_reader.jpg)\n","description":"Three interesting new engineering projects have come in: a microplate reader subsystem for water quality assays; a sensor front end with very stringent size, weight, and power (SWaP) constraints; and a scanning microscopy development system.","tags":[],"title":"Three New Projects","url":"/blog/three-new-projects/"},{"categories":["News"],"content":" I\u0026amp;rsquo;ve been retained by Banyan in a patent interference case regarding concentrator-type solar collectors.\n","description":"I've been retained by Banyan in a patent interference case regarding concentrator-type solar collectors.","tags":[],"title":"New expert case: Morgan Solar v Banyan Energy","url":"/blog/new-expert-case-morgan-solar-v-banyan-energy/"},{"categories":["News"],"content":" After almost exactly three years waiting for a claim construction ruling, this case has gotten started again. I\u0026amp;rsquo;m working on the trade secret side of a complicated suit arising out of a contemplated acquisition that wasn\u0026amp;rsquo;t completed.\n","description":"After almost exactly three years waiting for a claim construction ruling, this case has gotten started again. I'm working on the trade secret side of a complicated suit arising out of a contemplated acquisition that wasn't completed.","tags":[],"title":"The mountain hath been in labour....TAOS v Intersil is going again","url":"/blog/the-mountain-hath-been-in-labourtaos-v-intersil-is-going-again/"},{"categories":["News"],"content":" I\u0026amp;rsquo;ve been retained in NTRI v LG Electronics et al., another optical disc patent infringement case.\n","description":"I've been retained in NTRI v LG Electronics et al., another optical disc patent infringement case.","tags":[],"title":"Another New New Expert Case","url":"/blog/another-new-new-expert-case/"},{"categories":["Expert Witness Cases"],"content":"Testifying defense expert in an action for patent infringement concerning solid-immersion microscopy and laser voltage measurement in semiconductors.\nRecent items:\nApril 2012: Wrote claim construction declaration; May 1, 2012: Gave deposition in support of claim construction declaration; May 23, 2012: Assisted in tutorial December 2012: Case settled ","description":"","tags":[],"title":"DCG Systems, Inc. v. Checkpoint Technologies, LLC","url":"/blog/dcg-systems-inc-v-checkpoint-technologies-llc/"},{"categories":["News"],"content":" A case I\u0026amp;rsquo;ve been working on since March 2012, DCG Systems v Checkpoint Technologies, has settled, and I\u0026amp;rsquo;ve been retained in two others, ThinkOptics v Nintendo et al. (helping ThinkOptics with an inter partes reexamination), and Voxpath RS v Desay et al. (defending Samsung in an optical disc case).\n","description":"A case I've been working on since March 2012, DCG Systems v Checkpoint Technologies, has settled, and I've been retained in two others, ThinkOptics v Nintendo et al. (helping ThinkOptics with an inter partes reexamination), and Voxpath RS v Desay et al. (defending Samsung in an optical disc case).","tags":[],"title":"Two New Expert Cases, One Settles","url":"/blog/two-new-expert-cases-one-settles/"},{"categories":["News"],"content":" I\u0026amp;rsquo;m designing two brand new front ends for a scanning surface voltage tool for semiconductor manufacturing. Normally there are two ways you can measure surface potential—the vibrating Kelvin probe, which gets you the actual voltage but is very slow, or the fast-scan method, which is fast but gets you only the 1-D derivative of the potential.\nWorking with a leading semiconductor tool vendor, I\u0026amp;rsquo;ve come up with both an improved transimpedance front end and (more interestingly) a new class of front end amplifiers that should be able to get the actual voltage like the Kelvin probe while going fast like the scanning method, while providing at least 15 dB SNR improvement over either one.\nUpdate, March 3 2013: The TIA is done, and the new concept is underway.\n","description":"I'm designing two brand new front ends for a scanning surface voltage tool for semiconductor manufacturing. Normally there are two ways you can measure surface potential—the vibrating Kelvin probe, which gets you the actual voltage but is very slow, or the fast-scan method, which is fast but gets you only the 1-D derivative of the potential.","tags":[],"title":"Two New Front Ends for Scanning Surface Voltage Tool","url":"/blog/two-new-front-ends-for-scanning-surface-voltage-tool/"},{"categories":["News"],"content":" (We can\u0026amp;rsquo;t show ours due to NDA requirements\u0026amp;ndash; this is a cool one from Brown University that uses plasmonics.)\nWe\u0026amp;rsquo;ve just started a collaboration with a prominent biotech company in California on spectroscopic-detection biochips using photonic waveguides. Our part of the effort is to explore the design space and come up with new topologies to maximize signal-to-noise ratio and measurement stability. This is an excellent application for POEMS as well as being an exciting new area for us.\n","description":" (We can't show ours due to NDA requirements-- this is a cool one from Brown University that uses plasmonics.) ","tags":[],"title":"Photonic Biochips","url":"/blog/photonic-biochips/"},{"categories":["Expert Witness Cases"],"content":"Testifying defense expert in an action for patent infringement in GBIC optical transceivers. Advised and performed some reverse engineering.\n(settled quickly in 2011)\n","description":"","tags":[],"title":"Finisar Corp. v. Oplink Communications, Inc.","url":"/blog/finisar-corp-v-oplink-communications-inc/"},{"categories":["Expert Witness Cases"],"content":"March-June, 2009.\nHolland ACS470 This was my first expert case, beginning shortly after I left IBM. It was a patent infringement case concerning real-time spectroscopic optical sensors for precision agriculture, i.e. finding the condition of each plant or small region of a field, and applying just the right amount of fertilizer or pesticide. Precision agriculture is a win all round; it improves crop yields, prevents the spread of pests, while reducing the cost of chemicals and minimizing the runoff of those chemicals into waterways and ground water.\nThe technology was relatively simple: LEDs and photodetectors with filters, followed by amplifiers, filters, digitizers, and a bunch of software. The defendant was a garage startup whose sensors worked, and the plaintiff was a larger company whose sensors (I\u0026amp;rsquo;m told) did not work nearly so well. The defendant was not in fact infringing, but would probably have run out of money and so lost by default, except that their distributor (a …","description":"","tags":[],"title":"NTech Industries, Inc. v. Holland Scientific, Inc.","url":"/blog/ntech-industries-inc-v-holland-scientific-inc/"},{"categories":[],"content":" 160 North State Road, Suite 203, Briarcliff Manor, NY I\u0026amp;rsquo;m happy to announce that as of July 1, 2011, EOI is now in a larger and more convenient space, still in Briarcliff. As you can see in this photo tour, it provides a much larger lab area as well as a library/storage area and a second office for visitors and perhaps a colleague.\nEOI is very well equipped for electronic, photonic, and electro-optical design and prototyping, from the infrared to the ultraviolet and from DC to 40 GHz. As you can see from the equipment list, I have a very large and varied collection of optical, mechanical, and electronics parts of all sorts, that allows me to try new ideas out very quickly.\n","description":"160 North State Road, Suite 203, Briarcliff Manor, NY I'm happy to announce that as of July 1, 2011, EOI is now in a larger and more convenient space, still in Briarcliff. As you can see in this photo tour, it provides a much larger lab area as well as a library/storage area and a second office for visitors and perhaps a colleague.","tags":[],"title":"New Premises","url":"/blog/new-premises/"},{"categories":["News"],"content":" Besides info on do-it-yourself photoreceivers, I am introducing a new line of electro-optical products in cooperation with Highland Technology, a cutting-edge instruments company in San Francisco. The first product is a shot noise limited free space photoreceiver with quantum-limited sensitivity from 60 nW to 100 μW and an honest 1 MHz bandwidth (3 MHz on the 100 μW range). For photocurrents below a microamp, it\u0026amp;rsquo;s significantly better than even the bootstrapped cascode, and it comes in a nice module that fits your setup easily and has normal normal 1/4-20 and M6 threaded mounting holes.\nIt doesn\u0026amp;rsquo;t have some microscopic photodiode, either; the photosensitive area is 7 mm2, making alignment pretty easy even with very weak beams.\nUpdate February 24th, 2018: The PH200 has been discontinued, but you can get an even better one: the QL01 from Hobbs ElectroOptics\nPH200 photo Noise Plot of PH200 It uses a novel photon-coupled architecture, i.e. it\u0026amp;rsquo;s a current feedback design …","description":"Besides info on do-it-yourself photoreceivers, I am introducing a new line of electro-optical products in cooperation with Highland Technology, a cutting-edge instruments company in San Francisco. The first product is a shot noise limited free space photoreceiver with quantum-limited sensitivity from 60 nW to 100 μW and an honest 1 MHz bandwidth (3 MHz on the 100 μW range). For photocurrents below a microamp, it's significantly better than even the bootstrapped cascode, and it comes in a nice module that fits your setup easily and has normal normal 1/4-20 and M6 threaded mounting holes.","tags":[],"title":"PH200 Nanowatt Photoreceiver","url":"/blog/ph200-nanowatt-photoreceiver/"},{"categories":[],"content":" This book is an attempt to provide a systematic and accessible presentation of the practical lore of electro-optical instrument design and construction: in other words, it\u0026amp;rsquo;s the book I needed as a graduate student, but couldn\u0026amp;rsquo;t find.\nIt\u0026amp;rsquo;s intended in the first instance for use by oppressed graduate students in physics and electrical engineering, who have to get their apparatus working long enough to take some data before they can graduate. When they do, they’ll find that real-world design work has much the same harassed and overextended flavor, so in the second instance, it’s intended as a self-teaching guide and professional reference for working electro-optical designers.\nFor the third edition (February 2022), the book has been fully revised, and is almost a third again the size of the second edition, besides bringing in things learned in twelve years of consulting with EOI. The large format also made it possible to include a revised and expanded version of the …","description":"Building Electro-Optical Systems by Phil Hobbs","tags":[],"title":"Building Electro-Optical Systems: Making it all Work","url":"/pages/book/"},{"categories":[],"content":" Equipment — a partial list of EOI\u0026amp;rsquo;s lab equipment Lab Tour — photos from around the EOI lab ","description":"EOI's lab equipment, facility, and team","tags":[],"title":"Capability","url":"/pages/capability/"},{"categories":[],"content":"Consulting Services I got started in consulting during my 20 years as a Research Staff Member at IBM T. J. Watson Research Center. I began in the Manufacturing Research department, building special instruments for unique manufacturing problems for which commercial solutions did not exist, such as scanned-probe and solid-immersion microscopy, and in-chamber particle detection. I also did a fair amount of firefighting, retrofitting semiconductor lithography equipment for new capabilities, and helping fix problems that were causing immediate revenue loss in manufacturing. Later I developed new classes of computer input device, advanced scanning technology, and a new class of photonic detector and switch for optical interconnection, based on metal-insulator-metal tunnel junctions.\nFront of Watson Research The clear practical emphasis has never left me. One of the reasons that I wrote three editions of Building Electro-Optical Systems was to help people to build better products and …","description":"Consulting Services","tags":[],"title":"Consulting","url":"/pages/consulting/"},{"categories":[],"content":"With more than 30 years\u0026amp;rsquo; experience designing electronic, optical, and mixed-technology systems, and 43 US patents issued or pending, I have amassed a lot of expertise in a number of fields, including optics, optoelectronics, electro-optics, photonics (especially silicon photonics), analog electronics, optomechanics, optical and atomic force microscopy, semiconductor processing, signal processing, simulation, electromagnetics, due diligence, and the drafting and technical interpretation of patents.\nExpert witness work is one natural application, and I\u0026amp;rsquo;ve been testifying expert in 35 matters to date, including inter partes reviews and cases in district court and before the International Trade Commission. I\u0026amp;rsquo;m expert in optics, photonics, microscopy, and analog electronics, as well as some areas of semiconductor processing, metrology, and testing. I\u0026amp;rsquo;ve also written about 150,000 lines of C++ code, mostly for electromagnetic simulation, instrument control, and …","description":"Expert Witness Work History","tags":[],"title":"Expert Witness Work","url":"/pages/expert-work/"},{"categories":[],"content":"Here\u0026amp;rsquo;s a list of links to PDFs of the patents on this site. A few of these cases were also filed overseas. We\u0026amp;rsquo;ve also recently filed a provisional application on the thermal Faraday shield.\nI also do a fair amount of expert witness work in patent and trade secret cases. I\u0026amp;rsquo;m always interested in new work, so send me an email and let\u0026amp;rsquo;s talk about your application.\nSolar Photovoltaics US08569616: METHOD OF CONCENTRATING SOLAR ENERGY US08026439: SOLAR CONCENTRATOR SYSTEM Quantum Computing US07889992: HYBRID SUPERCONDUCTOR OPTICAL QUANTUM REPEATER Optical Interconnection US08528805: METHOD AND APPARATUS PROVIDING FINE ALIGNMENT OF A STRUCTURE US08104668B2: METHOD AND APPARATUS PROVIDING FINE ALIGNMENT OF A STRUCTURE RELATIVE TO A SUPPORT US20080310808A1: PHOTONIC WAVEGUIDE STRUCTURE WITH PLANARIZED SIDEWALL CLADDING LAYER US20080180340A1: WAVEGUIDE COUPLING DEVICES US20080285920A1: COUPLING ELEMENT ALIGNMENT USING WAVEGUIDE FIDUCIALS US20090003762A1: CHIP TO CHIP …","description":"List of Phil Hobbs' Patents","tags":[],"title":"Patents","url":"/pages/patents/"},{"categories":[],"content":"EOI works with customers of all sizes, from garage startups and university research groups to the largest companies in the electronics, defense, biomedical, and semiconductor equipment industries. We do research, technology selection, product design, IP licensing, and expert witness work in both patent and trade secret cases. We\u0026amp;rsquo;re always ready to help with debugging and firefighting as well—we learned some of this stuff the hard way too.\nUltrasensitive Instrument Design Complete Designs and Prototypes Featured Product: LA-22 Low Noise Lab Amplifier The LA-22 Low-Noise Laboratory Amplifier, 800 Hz–22 MHz, 1.1 nV / √Hz One problem that comes up again and again in doing measurements is that we need the apparatus to be quieter than the thing we\u0026amp;rsquo;re measuring, ideally by at least a factor of two. Besides quiet, it should be wideband, have an accurately known gain that\u0026amp;rsquo;s flat with frequency, have a clean step response, and generally do its job while keeping itself out of …","description":"Recent Work","tags":[],"title":"Recent Work","url":"/pages/recent-work/"},{"categories":[],"content":" Good Books — classic books on electro-optics and circuits, in softcopy sci.electronics.design — posts from the SED newsgroup archive ","description":"Books and reference material","tags":[],"title":"Resources","url":"/pages/resources/"}]